The superior density fiberglass is so far more dense than the medium and low density fiberglass that it looks like it should really reduce the probable for convection throughout the batts, but at two to 3 times the cost of medium density fiberglass batts the acquire may very well be nominal and not worth the added Price tag. Many thanks for sharing your knowledge,
I thanks for this impeccably timed weblog, as I am now framing my semi-primary cathedral ceiling hip roof (with limited ridge). I would like to explain my detail and take a look at to comprehend exactly where I'm on the proper monitor and even more importantly, the place I could have failures. Hope I can amuse several of you...I really feel just like the a lot more I try out to address a priority, the greater of a priority it gets, And that i certainly don't want to just take wonderful time, treatment, and detail to facilitate the demise of my roof.
"The common roof ventilation need used in creating codes and asphalt roofing brands requires 1 sq. foot of "Internet no cost ventilation space" for every 300 sq. ft of ceiling region (attic floor location) when vents are evenly divided — 50 % of them superior on the roof in the ridge, gable, or simply a significant roof, and fifty percent low around the roof on the eaves.
Lots of spray foam roofing contractors inside our industry are touting their ability increase effectiveness on old hot tar and graveled flat roofs by adding three to 4 inches of shut cell spray foam. The majority of these aged residences are flat roofs joisted with dimensional lumber, with parapets and have stucco vents Lower into the rim joists.
I suspect that Invoice Rose is right: all these failures include moisture that may be carried by moving air. They are not diffusion failures. Should the rafter bays seriously are effectively dense-packed -- a big if -- the prospect of air motion is incredibly small.
Many thanks - This is certainly new construction, I'm the designer / builder, and the greater I evaluate it, I am liking all rigid - less fussy. The best layer of rigid over fluffy would make my eave way too thick in any case. The air barrier with the T&G ceiling is really the sandwich of felt and taped three/8" CDX.
I was skeptical of Invoice Hulstrunk's claim that AccuVent baffles could face up to being dense-packed in an enclosed cavity.
In the alternative, if we straight from the source will not do a ventless roof this way, can we achieve our complete insulation demands by combining the above and underneath deck R-Values if we top all of it that has a vented in excess of-roof? Many thanks for your time and energy and your assistance! Dan
Admittedly these are new products for People but they have been utilised successfully in Europe For some time - so not really new. It will be appealing to find out how the set up is adapted to he said our industry.
I'm hoping to come to a decision with a roof venting tactic for my future job; a story and 50 % cape with twelve" double 2x4 partitions with dense pack cellulose for R-forty, and 2x10 rafters created down from within just like a Larsen Truss to 18" depth to accomplish R-sixty, also dense packed cellulose. On the inside, I would prefer to use Intello for vertical walls and taped cdx on sloped ceilings.
Many thanks Martin - Now I see why my first plan for a SIPS envelope was so elegantly uncomplicated. It seems like min R-ten sprayed under the roof sheathing and after that a complete-fill on the bays with batt / fluffy, in addition to a vapor sealed drywall lid can get me the 'scorching' (unvented) roof technique the SIPS was from the get go.
Also, wouldn't the internet site-constructed plywood baffles involving the rafters contain the exact difficulty; gradual drying via diffusion? ( I suppose I could use fiberboard for baffles)
Your blogs on this subject have been incredibly useful and I take pleasure in your guidance. ( I do study ahead of I post questions : )
Ultimately, makers began providing stiffer solutions which are greater capable to resist the pressures of dense-packed insulation. These goods occur and go, and plenty of are not readily available.